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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term management of mild to moderate pain and for the treatment of primary dysmenorrhea.
## Primary Indications
* Mild to moderate pain (e.g., dental pain, post-operative pain, musculoskeletal pain).
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg initially, followed by 250 mg every 6 hours as needed.
* **Primary Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed, usually started at the onset of bleeding and associated symptoms.
* **Maximum Dose:** Not to exceed 1250 mg per day for the first 2 days of treatment, then 1000 mg per day thereafter. The duration of treatment should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to a lack of established safety and efficacy data.
## Dose Adjustments
No specific dose adjustments are typically required for patients with renal or hepatic impairment, but caution is advised due to potential for organ toxicity with NSAIDs.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) bleeding or history of recurrent GI ulceration/bleeding.
* Severe heart failure, severe renal impairment, or severe hepatic impairment.
* Pregnancy in the third trimester.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, dizziness, headache.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis, and renal failure); hepatic toxicity; cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions (including anaphylaxis and severe skin reactions like Stevens-Johnson syndrome and toxic epidermal necrolysis); exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs and SNRIs:** Increased risk of GI bleeding.
* **Diuretics, ACE Inhibitors, ARBs:** May diminish antihypertensive effect and increase risk of renal dysfunction.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **GI symptoms:** Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* **Renal function:** Monitor electrolytes and renal function, especially in patients with pre-existing renal disease or those receiving concomitant nephrotoxic agents.
* **Hepatic function:** Monitor liver enzymes, especially in patients with pre-existing liver disease.
* **Blood pressure:** Monitor blood pressure, particularly in patients with hypertension.
* **Cardiovascular risk factors:** Assess and manage cardiovascular risk factors.
## Clinical Pearls
* Mefenamic acid is for short-term use only (typically not exceeding 7 days).
* Administer with food or milk to minimize GI upset.
* Use the lowest effective dose for the shortest duration necessary to minimize the risk of serious adverse effects.
* Be aware of the potential for cross-reactivity with aspirin and other NSAIDs in patients with asthma.
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**Disclaimer:** This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information or current clinical guidelines for comprehensive details. Always verify the most up-to-date information before making clinical decisions.
